The main purpose of a desktop computer is to have a personal computer in a centralised location. Having a more powerful computer in an accessible location like an office makes up for its lack of transportability.
A desktop computer contains more memory space than a laptop computer, meaning the computer can store more programs and files. A desktop also has a faster processor and higher quality sound and video cards. While the price may be more than that of a laptop, the amount of memory and speed provided often means consumers get more for their money.
Desktop computers contain more connection ports than laptops for connecting more external devices. This includes USB ports for keyboard/mouse peripherals as well as external hard drives or external disc burners. They also include full-size DVI ports while laptops usually only have mini-DVI connectors. Desktops also contain multiple PCI card slots for installing new hardware like updated video cards.
Desktop computers are not as transportable as laptops, but they can still work with laptops and other computers. Information can be shared with a laptop by connecting the two devices on a shared network via a router. Files and data can be transferred to a transportable device like an external drive and connected to another computer for file sharing.